Watts to kWh Calculator
Convert power (watts) × time (hours) to energy in kilowatt-hours.
kWh = (Watts × Hours) ÷ 1,000
Formula
W
hours
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Enter values above
How This Formula Works
Power (watts) measures the rate of energy transfer. Time (hours) measures duration. Multiplying them gives watt-hours (Wh). Dividing by 1,000 converts to kilowatt-hours (kWh) — the unit on your electricity bill and EV battery specs. A 7,200W (7.2 kW) charger running for 8 hours delivers 57.6 kWh — enough to fully charge most EVs.
Common EV Examples
Level 1 overnight
1,400W × 10 hours
14 kWh (~50 miles)
Level 2 at 40A, 8 hrs
9,600W × 8 hours
76.8 kWh
150 kW DC Fast, 20 min
150,000W × 0.33 hrs
50 kWh (~175 miles)
Cybertruck 80A charger
19,200W × 10 hrs
192 kWh
Tesla Supercharger V3
250,000W × 0.25 hrs
62.5 kWh
Monthly home charging
9,600W × 120 hrs/mo
1,152 kWh/month